.parent{
  width:500px;
  padding:20px;
  background:#ccc;
}
.a{
  padding:20px;
  background:#8c9eba;
}
.b{
  padding:20px;
  background: #109ef3;
}
.c{
  padding:20px;
  background: #6758f0;
}
.d{
  padding:20px;
  background:#52C41A;
}
.mt10{
  margin-top:10px;
}
.btn{
  width:auto;
  margin:20px;
}
